Signal device



March 9,, 33?, L CARR 2&73364 SIGNAL DEVICE Filed April 23, 1928 2 Sheets-Sheet l 6W 0 w W2 gi g 2&73364 March 9 M37, R. L. CARR SIGNAL DEVICE Filed April 23, 1928 2 Sheets-Sheet 2 Patented Mar. 9, 1937 UNl'lED srA rEs PATE'i orrrce aerator stems. navroa Application April 23, 1928, serial No. 272,01?

1 Claim.

This invention relates to a trafic control sys= tem and various instrumentalities particularly suited for use in such a system.

Mechanically actuated trafiic controlling de== vices now in use are commonly controlled chronometrlcally so that definitely timed periods are allotted to traffic in each direction no matter what the amount of that trafic may be and de spite variation of that tramc from time to time.

Hence mechanical devices of this character are unsatisfactory, particularly under comparatively light vehicular movement, since they tend unduly to delay traffic. As a consequence of the result= ing prejudice against devices of this character, l5 many intersections are not provided with traifdc control means and are the scenes of frequent accidents. I

The present invention is intended to obviate objections of this character and to afford traidc 29 control devices which are adaptable to a wide variety of conditions, being adapted to perform some or substantially all oil the functions com= ruonly performed by a traffic oficer. Systems of this character may be provided to take care of pedestrian as well as vehicular tlafdo and may be arranged in commotion with timed systems to work alternatively or optionally therewith. To this and means may be provided whereby the trafic control signal is automatically actuated in 3 response to the movement of vehicles toward intersection, means being provided to permit a vehicle to have suficient time to pass from the point or" signal actuation to the intersection, and means being provided to delay the effect of the impulse imparted by a vehicle if the signal is under the control of another impulse holding it in an adverse position. Thus a signal of this character ordinarily will continue to permit trafiic to how in the same direction as long as vehicles approach the intersection with less than a predetermined gap therebetween, although an indefinite succession of vehicles may be kept from indefinitely maintaining the signal in the same position, so that after a certain time an opportunity is aiiorded even for very light cross traific to interrupt the constant stream of vehicles tending to hold the signal in the same condition.. It is thus evident that means are provided to permit traflic to move at a comparatively high rate of speed past intersections, to give a positive warning signal if the right of way is not open to a vehicle, and to be adaptable to use in widely varying traffic conditions.

The above and further objects and advantageous features of the invention will be apparent (C11. Flt-33?) to those skilled in the art upon a reading of the subjoinecl description and claim in conjunction with the accompanying drawings, in which:

Fig. l is a wiring diagram showing one exempl'uication of the invention;

Fig. 2 is a sectional detail showing one end of the signal actuator as it is secured to the road bed;

Fig. 3 is an enlarged section on line of Fig. 4;

Fig. 4 is a transverse sectional view of a portion of a roadway to which the actuator is ap= plied, this view also showing the preferred means of mounting the control switch in relation to the actuator;

Fig. 5 is a sectional detail of a portion of the chronometric control means utilized in conjunction with one embodiment of the invention;

Hg. 6 is a View partly in broken elevation and partly in section of one form or signal control switch;

Fig. 7 is a similar view oi a primary switch showing a portion of the operating connection between the same and the actuator;

Fig. 8 is an enlarged section on line 83 of Fig. 7.

My trafilc controlling system may be actuated by any suitable means adapted to be operated by vehicles approaching the intersection at which the control signal is located. The latter may be of more or less conventional type and may comprise a plurality of lights located behind colored lenses each arranged simultaneously to send out red and green (or other colored) emanations at right angles to each other. Any suitable actuator or street traiiic detector, whether operated by radio waves, by photoelectric means, or by any suitable means for transmitting an impulse to a control switch for the signal light, may be used. Figs. 2, 3 and 4 show, however, the preferred embodiment of actuator or street trafic detector which is of a mechanical type. This actuator comprises a depressible treadle l disposed at the surface of the roadway and, if desired, located in a shallow trench 2, Fig. 3. This treadle may be of any suitable type but preferably comprises a flexible metal ribbon or connection 3 embedded in a yieldable carcass G which may resemble in texture a. pneumatic tire casing, being built up of laminae of woven fabric impregnated and vulcanized in a suitable rubber compound, or textile and wire fabric similarly treated, Member 4 may be slightly arched, as viewed in cross section with the metal ribbon 3 at the higher portion of the arch. One end of the strip 3 is formed into an eye 5 which engages a ring 6 on the spike 'I which is driven downwardly into the roadway in order to anchor the actuator in place. Preferably this end of the actuator is located adjoining the transverse center of the roadway so that it will at least be engaged by the wheels at one side of a vehicle that is approaching the intersection.

Adjoining the gutter is located a suitable box 3 which contains the control switch or similar mechanism. Preferably this box is located considerably above the surface of the roadway so that it may be removed from the moisture which tends to collect upon the same; thus the box may conveniently be secured upon any suitable post In. The carcass 6 preferably terminates ad- Joining thelower portion of the post and the metal ribbon 3 or the like is turned upwardly about a suitable idler pulley or bar II, the flexibility of this ribbon permitting it to turn about the member The vertical run of flexible member 3 may include any suitable adjusting means such, for example, as a turnbuckle l3. From an inspection of Fig. 4, it will be evident that the intermediate portion of the actuator,

the position of which is determined by member 3, is arranged to be substantially taut, since member 3 extends in a substantially straight line from idler H to ring 6. Since the inner end of the actuator is thus raised somewhat from the surf-ace of a normally crowned roadway, the gutter portion of this surface may be provided with suitable humps It at each side of treadle I. The upper end of member 3 is yieldably supported within the box 9 as presently will be described; accordingly the former is normally held taut somewhat above the level of the roadway so that a vehicle wheel passing over the actuator will depress the same and will pull downwardly upon the vertical run of member 3 in order to actuate the mechanism within box 3.

Fig. 7 illustrates in greater detail one type of mechanism which may be operated in this manner. In this figure the upper end of member 3 is shown connected to a vertically slidable plate 20. This latter is secured to a suitable block 2|, indicated in.dotted lines, the block and plate together being slidable in a suitable guide 23 which is secured to the supporting panel. The upper end of member 20 is connected to the lower end of a coil spring 25, the upper end of which is supported by a suitable bracket 21 projecting from the supporting panel. Thus the spring tends to pull members 20 and 3 upwardly and to hold the latter substantially taut, while movement of a vehicle over the actuator will cause the member 3 to pull plate 20 downwardly and will cause stretching of spring 25. Plate 20 preferably is provided with a suitable cam-like surface 28 which is designed to engage a switch-controlling member when this action occurs. Thus the surface 28 preferably may incline downwardly away from the switch operating member 30 in order gradually to engage and move the same upon downward movement of plate 20.

Member 30 is disposed at the outer end of a bent arm 3|, a portion of which may be slotted, as designated by numeral 32, and may be engaged by the armature 33 adjoining magnet 34. Above the latter, member 3| preferably is secured to a tiltable arm 35 which is mounted on a pivot 36 and carries resilient clips 31 that receive a suitable mercury container 33. This container may be of the conventional type used in mercury 7 switches, being filled with any suitable gas to eliminate or reduce arcing. Suitable leads 39 and are connected to one end of the mercury tube, being arranged so that tilting of the tube inone direction closes a circuit therebetween. Above the tube I preferably provide a suitable weight 44 in order more readily to cause member 35 to leave its horizontal position and to swing downwardly in one direction or the other. A suitable depression 46, shown in dotted lines, is located in weight 40 and receives the lower end of a swinging member 52 that is mounted upon a pivot 50, the latterbeing ofiset slightly to, one side of the pivot 35 about which member 35 tilts. The upper end of member 52 carries a pair of resilient clips 53 which receive a second mercury tube 54. The latter preferably contains a swinging closure 56 pivotally mounted therein so that the closure may swing to the position indicated by dotted lines in Fig. '7 when tube 56 is tilted in one direction. When the tube is tilted in the opposite direction (having a more gradual inclination in this position due to the location of pivot 50), a suitable stop 51 prevents the closure from swinging past a position at right angles to the longitudinal extent of tube 54-. The lower end of closure 56 is shaped to provide a restricted passage 58 along the bottom of the tube. Suitableelectric contacts are located in the end of the tube toward which the closure is permitted to swing, one of these contacts being connected to the lead 40 from tube 38 andthe other being connected to a suitable lead 60.

One end of member 35 is extended and connected to suitable means 59 for delaying its movement in one direction. Such means may comprise a suitable piston 6| movable within a cylinder 62 which is partially filled with any suitable liquid, such as oil. The cylinder may be provided with a plurality of by-pass ducts 63' connecting its upper and intermediate portions,

, while the piston may have ports 63 elongated in a direction parallel to the piston axis near its head and may have smaller ports 65 in the lower portion of its skirt. Restricted openings 61 may be disposed in the head of the piston, as shown. When member 28 is moved downwardly due to the passage of a vehicle over the actuator,v the member 3| is swung about pin 36 and tube 38 is tipped so that an electrical current may pass between leads 39 and 40. At the same time tube 54 is necessarily tipped in the opposite direction, closure 56 being swung into engagement with stop 51; thus the major portion of the mercury in the tube is caught in the upper end thereof above closure 56, this mercury being able gradually to fiow downwardly through the restricted opening 58. Accordingly tube 53 with closure 56 aifords means maintaining the circuit controlled by tube 38 closed for a considerable length of time, but ultimately permitting this circuit to become opened. tilted to its inoperative position, gravity causes closure 56 at once to swing down to the position shown in dotted lnes and the mercury may immediately return to the end of the tube which contains the electrical contacts.

Energization of magnet 34 will tend to swing member 3| back to the position shown in Fig. "7. This movement will occur gradually due to the arrangement of ports 64 and 65, while movement of member 3| and tube 38 in the opposite direction may occur practically instantaneously. Thus when the latter movement occurs, any of the liquid above the piston will rapidly be lifted and may pass downwardly into by-pass ducts 63.

Obviously when tube 3 is through restricted passages 61.

When the piston reaches its extreme upward position, the lower openings into these ducts and the ports 65 will register so that the liquid will flow into the space below the piston. Downward movement of the piston will cause some oil or liquid to flow outwardly through ports 65 as long as these continue to register with the openings into the by-pass ducts. Upon continued movement of the piston, these openings will be closed and the liquid can only be forced out of the space below the piston by passing upwardly Accordingly movement of the parts connected to the piston is delayed until ports 64 start to register with the lower openings into the by-pass ducts, when free flow of the liquid is again permitted and the latter part of the movement of the swinging parts toward the position shown in Fig. I can occur quite rapidly. Thus, whilethe energization of magnet 34 will cause the tube 38 to tend to tilt to a position wherein the circuit between leads 39 and 40 is open, this movement will be retarded by the delay factor 59 until the tube reaches a. substantially horizontal position when the electrical circuit between leads 39 and 40 is opened, whereupon the arrangement of ports 64 permits the latter .part of the movement to be concluded almost instantaneously.

It will be understood that the above-described actuators are located on each roadway at some distance from the common intersection and that the primary switches are connected by suitable electrical leads with the control switch which directly controls the energization of the signal lights.

Fig. 6 illustrates a portion of one form of such a control switch with related parts. This switch comprises the tilting member 10 carrying the mercury container II and pivotally mounted upon pintel I3. Depending from member I is a suitable arm I4 having an opening 75, indicated in dotted lines, through which the armature rod 16 passes. This rod carries two armatures II which are disposed adjoining the ends of opposite electromagnets I8. The magnets I6. are arranged to cause tilting of member I0 and tube Ii in one direction or the other. The lower end of arm I4 preferably is connected to a suitable electric lead 80 and is adapted in its extreme positions to engage one or the other of a pair of electrical contacts 8i. The ends of member 70 are each connected to suitable retarding mechanisms 59* which in general resemble the mechanism 59 described above. However as shown in Fig. 6, the mechanism for the control switch may be provided with a piston having lower, somewhat elongated ports 65 so that the maximum retarding effect or delay takes place when the member 10 and tube 1 I.a re near or just leaving their horizontal positions. Tube II preferably is provided with three pairs of electrical contacts, the central pair being extended downwardly into the tube further than either of the end pairs, so that when the tube containing a proper quantity of mercury is substantially horizontal, a current may onlypass between the intermediate pair of contacts and so that tilting of the tube to either of its extreme positions will close a circuit through one of the end pair of contacts, leaving the other circuits open. A suitable weight 82 is connected to member 10 in order to facilitate movement of this member from its horizontal position.

Fig. 1 indicates diagrammatically the relation of the primary and control switches, the former being designated in general by letters N, S, E, and W respectively, it being understood that mechanisms N, S, E, and W are located at determined distances from the intersection of the roads, the illustration presented herewith representing a conventional arrangement for an ordinary four comers. It is of course obvious that when right of way is allowed for north-bound trafiic, under most conditions rt will also be al lowed for south-bound traflic, and accordingly -the typical example presented herewith illustrates the north and south Switches and the east and west switches respectively in parallel.

The lead 85 from one side of the source of electrical current has an extension 85 with branches I50, I5I and I52 extending into the ends and the intermediate part of the tube II, as shown, and the lead I86 forming a branch of the lead I86 of the other side of the source of current supply has corresponding branches I60, I6I and I62 in which the lights GN, 0 and GE are disposed in series, the ends of these leads terminating in contacts in the tube I I. Thus the ends of leads I52 and I62 will contact the mercury in the tube II when it is tipped to the position shown in Fig. l to energize the light GE. When the tube is in a substantially horizontal position, the ends of. leads I 5| and I6I will both engage the mercury, while the ends of leads I60 and I52 will be out of engagement with the same; accordingly only the light 0 will be energized when the tube is in this position. When the tube is tipped in a direction opposite to that shown in Fig. 1, the current will pass through leads I50 and I60 to energize light GN.

A branch 80 of the main lead 85 is connected to the arm I4 supporting the tube II and thus permits current to pass to one or the other of contacts 8i which may be in engagement with corresponding fixed contacts 8i. Each of the latter is connected to one of two parallel leads 06, each of which is connected to a pair of parallel switch assemblies. Thus when contacts 8i and 3i engage each other, current will pass 'from one side of. the line through lead 80, contacts 8i and M and one of the leads 86, through its branches 86*- to the magnets 34 of switch assemblies N and S, or E and W, thence passing through return leads 0'! to the main lead I86 at the other side of the line. It is thus evident that when the tube II and arm I4 are tipped to either one or the other of their extreme positions a contact BI will engage a contact ill to cause current to pass through two of the magnets 34 which are in parallel and thence be returned to the other side of the line. Each tube 38 is connected by a lead 39 with the main lead I86 and to the adjoining tube 54 by a short lead 40. Leads 60 extend in parallel from tubes 54 to join one of the two leads III] that is connected to one of the two magnets I8, these magnets being connected through the leads 85 and 65* respectively to the main lead 85. It is evident that the leads 60 from the switch assemblies E and W are connected in parallel to one of the controlv magnets I8 and that the corresponding leads 60 of the other two switch assemblies N and S are connected to the other magnet. Accordingly the energization of one of the magnets I8 will occur when a tube 38 is tipped to a position wherein the mercury therein permits current to pass through the corresponding leads 39 and 40, the tube 38 of the switch assembly W being shown in this position in Fig. 1. With the tube in this position as long as the mercury permits current to pass through the upper part of switch 54 the current coming from lead l88 will pass through lead 39, the mercury in tube 38, lead 40, the mercury in tube 55, leads 6B and ill], and the corresponding magnet 18 and thence through return lead 35 to the other main lead 85, Obviously when the mercury leaves the upper part of tube 84 this circuit is broken.

As shown in Fig. 1, one signal light may be energized respectively by each of. the three pairs of contacts which are located at the respective ends and the middle of switch tube H. Thus the light GE may show a green light for eastand west-bound traffic and a red light for northand south-bound traflic, while the light GN may show green for northand south-bound traffic and red for eastand west-bound trafiic. The intermediate light 0, the use of which is optional, may be orange and may indicate that the signals are changing, thus giving drivers of vehicles which are approaching the intersection an opportunity to stop if the light isabout to turn against them. Obviously the tube H tips in response to the attraction of one or the other of the armatures by magnets 18, and when both of these magnets are simultaneously actuated, the tube will tend to be controlled by the magnet which is the nearest to its respective armature or, if the tube is in its extreme position under these conditions, it will remain stationary. Each of the magnets! is connected to one of the pair of parallel primary switch assemblies. Thus assembly W (Fig. 1) is shown with the tubes in the position which they occupy when the switch has just been actuated, tube 38 being tilted to a position wherein the circuit is closed between leads 39 and 40, the mercury being maintained,

however, in the upper portion of tube 54 so that the circuit through that tube remains closed. Accordingly the leads 39 being connected to one side of a suitable source of electric power and a lead 85 with branches to each of magnets 18 being connected to the opposite side of said source of energy and one of these magnets being connected to each pair of primary switches, one of the same is energized upon the operation of any actuator I by the movement of a vehicle thereover. Thus this magnet tends to'cause the tube H to tilt to cause the corresponding signal light to be actuated so, as shown in Fig. l, the tube is positioned so that light GE is being energized. The magnets 34 are connected by leads 86 with contacts 8i; thus tipping of the tube to its extreme position results in the closing of the circuit between lead 80 and one of. the leads 86, whereby one of the pairs of magnets 34 is energized in order to return a corresponding tube or tubes 38 to inoperative position. Thus, as shown in Fig. 1, magnets 34 of assemblies E and W are both being energized to return the tubes 38 of the east and west switches from their operative positions.

This movement is delayed, however, by the factor 59 in each case so that a definite time may elapse after the control switch circuit is closed before it is opened. Similarly the delay factor 59 for the control switch retards movement of this member, tending, however, to hold it in a horizontal position wherein the circuit between the intermediate pair of contacts may be closed, thus causing the orange light 0 to be energized for a second or two whenever the signal is changing from one position to another. Due to the arrangement of ports 64 and 65 the movement of the tube H up to horizontal position may be practically instantaneous, while its movement as it leaves this position is at first considerably retarded. Thus re-energization of the magnet which the armature has just left is not likely to cause the tube to return to its previous position once the orange light is energized. Obviously repeated energization of either one of the pair of parallel controlling magnets will send successive impulses to one of the magnets 78, thus tending to hold the tube tilted in the same position if it has already been swung to that position. Accordingly a succession of vehicles energizing either of the actuators which control primary assemblies E or W will cause successive impulses to be sent to the corresponding mag-' net 18 so that the tube 1! will remain in the same position and light GE continue to be energized no matter what the condition of the energizing magnets N or'S.

Assume, however, that either magnet N or S is energized and that a gap of more than a few seconds occurs between the vehicles which are moving either east to west or west to east as they approach the corner. Thereupon, the magnets 34 being energized, the tubes 38 in assemblies E and W will be moved from their switchcontrolling position, the corresponding magnet 18 will no longer be energized, and tube H may tilt in an opposite direction. It is accordingly evident that the signal device tends to continue to remain in the same condition as long as vehicles continue coming in the same or a direct- 1y opposite direction with less than a determined time. interval therebetween this time interval being determined by the delay mechanisms 59 and 59 It will be further evident that a magnet 18 will continue to be energized until the armature is drawn toward that magnet, whereupon correspondingmagnets 34 are energized to open the circuit which controls the said magnet 18.

However, inorder to prevent a constant stream of vehicles from monopolizing the right of way, the tubes 54 are so arranged that the mercury will drain out of their upper ends in a determined period of time, thus opening the circuit between the corresponding leads B0 and 40. Thereupon, as soon as each of the parallel circuits is thus opened due to continued movement of vehicles in this manner, the corresponding magnet 78 can no longer be energized and energization of the opposite magnet, 18 even by a single vehicle will be enough to change the condition of the trafiic lights.

From the foregoing it is evident that this system does not favor the movement of vehicles in one direction to the exclusion of a transverse direction. Accordingly this traffic signal is adapted to use at the intersection where the traffic approaching in directions at right angles to each other may be of substantially the same volume. The signal will remain in the condition in which it was put by the last vehicle until another vehicle approaches Thus, referring to Fig. 1, assume that any magnet 34, such as that of switch assembly W, has been energized long enough to cause the tube 38 to be attracted thereto against the retarding influence of factor 59; then the current will no longer pass between the leads 39 and 40 which enter this tube 38 and the corresponding magnet 18 will no longer be energized as a result of the same. As long, however, as

there is nothing to cause the tube II to swing away from the position to which it was thus attracted, itwill remain in this position, leaving the same when the other magnet 18 is energized, as a result, for example, of the tipping of the tube 38 of the N or 5 switch assemblies.

Assuming that a plurality of vehicles are appreaching from the west, the tube 38 will tend tobe drawn toward the magnet 34 during the intervals between each successive engagement of the wheels of one of these vehicles with the treadle member 4, but the retarding factor 59 will delay this'tendency oi the tube 38 to move toward the magnet 34, thus permitting the vehicles from the west to approachwith a definite interval therebetween and permitting the tube 38 to remain tipped at an angle sufliciently great to ensure the constant flow of current through leads 39 and 40, and from the latter through tube 54 and leads 50 and Hi! to the corresponding magnet 18. Thus the tube II will be held in a position wherein current passes through leads I52 and I62 to the light GE which affords the right of way to the westand east-bound trafilc. Assuming that the succession of vehicles from the west continues, however, the mercury in the upper end of tube 54 will gradually trickle throughthe restricted opening provided by the closure 56. Thus within a limited time the current is prevented from passing from lead 40 to lead SDthrough this tube, and the corresponding magnet 18 is no longer energized. With the system in this condition the vehicles from the west may continue to have the right of way because there is nothing to tip tube H in the opposite direction, unless at least one vehicle has approached in a transverse direction to energize the opposite magnet 18 by the tipping of a tube 38 of either the switch assembly N or the corresponding switch assembly S. This magnet will remain energized while vehicles from the west continue to pass, since the tube 38 that causes this energization will not be drawn to its inoperative position by its control magnet 34 until the main control tube H has been tipped to give the right of way to the vehicle that has caused this energization of the magnet, when the current will be received through leads 86 and 86 to cause energization of the magnets 34 of assemblies N and S and accordingly movement of one or both of the tubes 38 of the assemblies N and S out of their operative positions.

It is thus evident that the tube .1 I and accordingly the trafiic lights GE or GN will remain in the same condition until a vehicle approaches in a direction to cause the tube 'H to be swung stream of vehicles approach in close succession right of way will be given to that line of vehicles for a definite period which is primarily determined by the tube 54 of that switch assembly, and that energization of the magnet 18 to swing the main control tube II in the opposite direction while this stream of vehicles is passing is sufflcient to cause a change in the condition of the signal lights as soon as the mercury has run out of the upper portion of the tube 54 of that switch assembly upon the roadway from which the traflic stream has been approaching.

I claim:

A traflic control system for intersecting traffic lanes including in combination an electric right of way signal, a switching means to operate the same to alternately accord right of way to the lanes, a pair of tubes for one of said lanes each containing mercury and having two spaced electrical conductors projecting into the tube, one of said tubes being normally biased in a tilted position to cause the mercury to be out of contact with the conductors, a linkage connecting said one tube with the second tube to cause the mercury in the second tube to be in contact with the conductors therein when the first tube is in its normal biased position, an electric circuit including said conductors in series, means operated by trafiic in said one lane to tilt said one tube to an oppositely tilted position to cause said electric circuit to be established thru the conductors and mercury, said one tube upon such tilting operating the linkage to tilt the second tube tending to cause the mercury thereof to separate from its conductors and said second tube including means retarding such separation of the mercury from its conductors for a time period while said second tube is so tilted, means including said circuit when so established to actuate said switching means to operate said signal to accord right of way to said one lane, means operated by said switching means when right of way is accorded to said one lane and including time delay means to cause said tube to be returned to its normal out of contact position after a time period, said tube adapted to be retilted into its contact making position repeatedly by repeated closely spaced operations of the traflic operated means to maintain said circuit established.

R.L.CARR.I 

